Automated perifusion systems offer the advantage of rapid analysis of the impact of various fluids on various samples. In an automated perifusion system, fluids are provided from a plurality of fluid sources and are pumped through a manifold where the fluids, or mixtures of the fluids, are then directed to designated sample containers. The output from the sample containers is collected in identified receptacles so that the user can analyze the collected fluid, and thereby the interaction of the source liquid or mix of liquids on the sample in the respective sample containers. Such systems are described in U.S. Pat. No. 8,865,427 and U.S. Pat. No. 8,263,389, the disclosures of which are herein fully incorporated by reference.